When there are two or more Quick Filters available, and one of them is on the Subtext attribute, once one of the other filters has its value changed the null text for the Subtext selection criterion (namely, "-- Text  --") is used as a genuine selection criterion, thus typically preventing any entries from matching. 

This is for v2.7.0-1961 with both Mozilla 2.0.0.9 and IE 6 on Windows XP Professional SP2, and I think has appeared with this release.  You can demonstrate the behaviour on this forum: 

• Go to http://midas.psi.ch/elogs/Forum/
• Quick filter on dates in the "Last Month" and nothing is listed.  The URL is now http://midas.psi.ch/elogs/Forum/?last=31&Subtext=--+Text+--
• Set the date filter back to "-- All Entries --" and the spurious subtext filter remains; the URL is now http://midas.psi.ch/elogs/Forum/?Subtext=--+Text+--
• Delete the "-- Text --" value in the filter box and everything reappears; the URL is back to http://midas.psi.ch/elogs/Forum/

Richard Stamper